1. Field of the Invention
The present invention relates to technology for processing to send video data, audio data, etc. over a network.
2. Description of the Related Art
In recent years, it has become comparatively easy to transfer multimedia data such as video data and audio data using a network, for example by transmitting video data taken with a camera to a terminal connected to a network, and playing back the received video data on the terminal.
Generally, processing to send the video data taken with the camera is performed by a control program executed by the camera, as described below.
First, when encoded data constituted from video data that has been compression encoded on a frame-by-frame basis according to MPEG (Moving Picture Experts Group) standard or the like is stored in a storage area in the camera, the stored encoded data is read and copied to another storage area that is different from the storage area that stored the encoded data.
The encoded data is copied to another storage area so that encoded data to be stored subsequently can be stored while transmission processing is performed on the packet data in parallel, as described later.
Next, for each predetermined size portion of the encoded data copied to the other storage area, a checksum is calculated, header information including the calculated checksum is generated, packet data is generated that includes the generated header information and the predetermined size of encoded data corresponding to the checksum, and the packet data is transmitted.
In this way, during send processing of the video data, since the encoded data is copied in the storage area, if the size of the encoded data is large due to the compression rate, etc., copying the encoded data takes more time, and the send processing time for each piece of encoded data increases.
Meanwhile, when sending video data, there is a need to send each piece of encoded data in a predetermined time period in accordance with a frame rate determined in advance by standards, etc., since if sending the piece of encoded data in the predetermined time period according to the frame rate is not possible, so-called jumpiness occurs, and the receiver of the sent video data cannot continuously play back the video.
As described above, send processing of large sized encoded data is time consuming, and high-speed send processing of each piece of the encoded data is necessary for sending the video data without jumpiness occurring.
As technology for high-speed send processing, a method is known in which send processing that is performed by the control program (software) in the above description is realized entirely with hardware (for example, Japanese Patent Application Publication No. 2001-268159, which is hereinafter referred to as “patent document 1”.)
Realizing send processing entirely with hardware enables suppressing the overhead of processing that occurs when send processing is realized with software.
However, in general, when send processing is realized entirely with hardware, the initial cost of manufacture increases.